This invention relates to an automatic carrying and metering system for a liquid reservoir to carry the reservoir containing liquid materials such as paint therein from a supply shelf to a metering station and to put the reservoir back in its original position in the shelf automatically. This system can be utilized to establish an automatic paint mixing and paint metering process in such a field as automotive paintings where a plurality of colors and types of paints are employed.
Paint metering designs in the past often utilized fixed displacement pumps, in which designs metering operation has been achieved through an extruding action of the fixed displacement pump. Such a metering system of the displacement type, however, does not readily lend itself to use for a small amount of paint such as 0.01-0.4 g by weight, resulting in an inconvenience of rather limited accuracy. Another problem is the fact that in order to deal with a plurality of colors and types of paints prior design requires a plurality of fixed displacement pumps corresponding to the number of colors or types of the paint, so that the metering device becomes complicated and color modification can not be easily attained.
One solution for this problem was proposed in our U.S. Pat. No. 4,585,148 issued on Apr. 29, 1986. In this apparatus, fixed displacement pumps being removed, a sliding valve mechanism is attached to each reservoir and its valve drive member is driven by a pulse motor automatically. However, in its arrangement, a plurality of reservoir bases are mounted around the circumferences of a rotary table, resulting in a problem that the diameter of the table becomes larger occupying ever greater space as the number of reservoir increases.